Systems, apparatus, and methods for informing an on-tractor navigation system of position of a towed implement. In one aspect, a non-GNSS sensor mounted on the implement provides heading information to the navigation system. Knowledge of the geometry of the implement along with navigation coordinate frame position information from the navigation system, allows a relatively economical and flexible way to derive implement position information without the expense of a GNSS receiver on the implement Adding inertial sensors on the implement can allow position determination of any point on the implement relative to the ground. This can be advantageously used for swath and rate control for implements.